1. Field of the Invention
The present invention is broadly concerned with a liquid distribution nozzle assembly which can be used to good effect in both counterflow and crossflow-type water cooling towers, and which is designed to safely pass relatively large particles and debris found in some cooling water streams while at the same time giving excellent water dispersal for enhanced cooling. More particularly, it is concerned with such a distribution nozzle assembly making use of an axial flow type water metering fixture together with a specially designed, strategically located target structure beneath the fixture designed to effectively break up and disperse impinging water into relatively small droplets over the area beneath and surrounding the nozzle for the most effective distribution for cooling of the water.
2. Description of the Prior Art
Electrical utilities and other types of large scale industrial plants generally employ water cooling towers handling the large quantities of hot water produced during plant operations. In towers of the crossflow variety, hot water is delivered to an elevated distribution basin, whereupon the hot water is permitted to gravitate therefrom through a series of orifices into a fill section and, ultimately, collection in a lower cold water basin. As the water gravitates through the fill section, ambient-derived air is drawn laterally through the fill in order to come into intersecting relationship with the hot water. It has long been the standard procedure with such crossflow towers to provide removable tubular nozzles in the distributor floor apertures. These nozzles are generally fabricated of corrosion resistant materials, and are provided with a central cylindrical body section which extends downwardly through a basin aperture and a relative large upper flange adapted to rest flatly on the floor of the basin around the aperture. Moreover, such nozzles are conventionally provided with a target structure beneath the tubular fittings which are designed to break up and disperse the gravitating water.
Another type of commonly employed tower is referred to as a counterflow tower. In such units, initially hot water is passed downwardly through the fill structure, while ambient-derived cooling air is brought upwardly through the fill in direct opposition to the descending water. As a consequence of this design, counterflow towers do not make use of overlying basins as such, but instead are provided with piping systems and associated outlet nozzles in overlying relationship to the fill structure.
U.S. Pat. No. 3,617,036 discloses a highly effective nozzle apparatus designed for use in crossflow-type cooling towers. The nozzle disclosed in this patent includes the described tubular fitting creating a downwardly directed, metered flow of water onto an underlying target device. However, nozzles as disclosed in this patent are not suited for use in counterflow-type towers.
On the other hand, U.S. Pat. No. 4,208,359 describes a very successful distribution nozzle specifically designed for counterflow towers. In this device a hollow-cone swirl-type upper nozzle is provided along with a lower target in the form of a plurality of circularly arranged buttons or fingers oriented for water dispersal purposes. Here again, nozzles as disclosed in this patent are extremely effective in the context of counterflow towers, but cannot be used in crossflow towers because of the need to create a hollow-cone swirl pattern, rather than providing a simple tubular fitting for axial water flow.
The counterflow-type nozzles described in U.S. Pat. No. 4,208,359 are designed for use in pairs with adaptors which straddle piping on five to six foot centers. Many existing counterflow towers, however, are piped on two and one-half to three foot centers, and are not provided with lateral distribution pipes designed to mate with the tangential tubular entryways forming a part of the upper swirltype nozzle bodies. Rather, such prior constructions simply include a plurality of parallel, spaced apart mains with depending, threaded nipples on two and one-half to three foot centers. As can be appreciated, in order to convert such prior counterflow towers to use nozzles of the type described in U.S. Pat. No. 4,208,359, considerable work and repiping is required, and this can amount to a significant expense.
In the operation of a plant water cooling system, it is a common practice to periodically place a number of foamed plastic or cellular synthetic rubber-like balls into the cooling water in order to clean and clear out plant heat exchange tubes. The balls are sized to be slightly larger in diameter than the pipes through which they are passed for cleaning purposes, and are generally available in diameters ranging from about one-half inch up to about one and one-half inches. Given this practice, it is important that water cooling towers, and particularly the nozzles forming a part thereof, be constructed so as to accommodate flow of such balls therethrough. Even though the cleaning balls are designed to be removed after each use thereof, it normally follows that a number of the balls escape and remain in the system; hence the need to provide clearances for such balls.
Another related problem stems from the fact that many cooling waters, such as those taken directly from rivers, contain significant amounts of debris. In certain cases clams and crabs can also be taken up in the cooling water delivered to the tower, and as a consequence the distribution nozzle must also be able to safely accommodate debris of this type without clogging.